1. Field of the Invention
The present invention relates to a chip mounting device and a method of alignment thereof, and specifically to a chip mounting device capable of performing high-speed and accurate alignment and an alignment method in the chip mounting device.
2. Discussion of the Related Art
As well known, in a conventional chip mounting device, the position of a chip held by a head and the position of a substrate (for example, a liquid crystal panel, etc.) supported by a substrate holding stage disposed below the head are precisely positioned, and in this condition, chip mounting is performed by moving the head down.
In order to raise the working efficiency of the mounting operation and shorten the tact time in such a chip mounting device, a so-called rotary-head type chip mounting device is known wherein a plurality of heads are provided and each head is moved in order between a position for receiving a chip and a position for mounting the chip onto a substrate (for example, JP-A-7-193102).
On the other hand, chip mounting devices can be roughly classified into devices for bonding chips (bonders) and devices for mounting chips (mounters). A bonder bonds a chip held by a head to a substrate by heating and pressing. A mounter basically does not heat a chip held by a head, but merely places the chip on a substrate or temporarily bonds the chip to the substrate, and thereafter the chip is permanently bonded by using a heating furnace, etc.
Generally, in a bonder, the positions of a chip and a substrate facing each other are recognized severally, at a position for mounting the chip onto the substrate immediately before mounting. For example, the positions of the chip and the substrate are recognized by two-sight recognition means, and after an amount in shift of the relative positional relationship therebetween is amended, the mounting operation is performed. The two-sight recognition means provided as a position recognition means is usually provided in a chip mounting device so as to be inserted before recognition and to be retreated after recognition. Thus, it becomes possible to bond a chip and a substrate at a high accuracy by controlling the positions based on the information of the relative positional relationship obtained by the two-sight recognition means. For example, it is possible to bond them at an accuracy of about 5 μm or less. On the other hand, because the two-sight recognition means is inserted and retreated at a chip mounting position, other operations cannot be performed during its operation, so there is a limit in shortening of the time of a series of operations in the device. Therefore, even if the device is constructed as a rotary-head type chip mounting device as described above, there is a limit in shortening of the tact time.
In a mounter, the construction of a rotary-head type chip mounting device is fairly popular, and therefore, high-speed mounting is possible. In this type of mounter, usually, the recognition of the position of a substrate is performed at a position separated from the chip mounting device and before the substrate is supplied to the chip mounting device. Therefore, the mounting operation in the chip mounting device can be performed in a short period of time, and the tact time of the device as a whole can be shortened. However, because an amount in shift of the relative position is not amended at the actual chip mounting position,the bonding accuracy of the substrate and the chip is not improved so much, and the accuracy is limited to a maximum of about 100 μm. Although such a mounter has been used for applications that do not require a high accuracy, recently the demand for high accuracy in a mounter has been increased, and therefore, the conventional mounter cannot satisfy the requirement.